Sulphur dyes, and process of making same



Patented Oct. 23, 1934 UNITED STATES ores, AND rnocsss or MAKINGSAME- SULPHUR PATENT OFFICE the sulphuration of n indophenol of thefollowv The invention relatesto sulphur'dyes and to a process for making ,suchdyes, and includes correlated improvements. and discoveries whereby and wherewith: the properties of the sulphur dyes are enhanced. yMaterial .dyed with thetnewdyes forms a part of theinvention. i

An object of the invention is to provide a proc- I ess; for-the production of sulphur. dyes from an indophenol and a polysulphide which shall give an increased yield of dye with greater efiiciency and with reductionin the cost of manufacture; 1

Another object of the invention is. to provide a process for the, production of sulphur dyes wherebythequantity of sulphur'remaining in the {finished dye is materially reduced, thus obviating dilutionof the dye and. liability to cause fire in the grindingmills; I A

j-Other objects of the invention areto producea blue sulphur dye which is soluble in aqueous so dium sulphide and which dyes materialblue shades from a sodium sulphide bath, and toprovide as an article of manufacture materialdyed blue shades vwithsucha sulphurdyeQ IL i 1 Other objects of 1 the invention will in, part be obvious and will in part appear hereinafter.

The particular method to which this invention relates isthat wherein an indophenolis heated with-alpolysulphide in thepresence of a solvent, e, g.,water, alcohol, etc. whichpolysulphide may be prepared by dissolving sulphur in alkalimetal monosulphide or in caustic alkali. At the end of the sulphurationthe dye is present in the sulphuration mass in a formwhich may be considered as being the reduced or leuco dye suspended i or dissolvedin the sulphide solution; The dye may be isolated from the sulphuration mass or meltby one of several methods, for example, by diluting the sulphuration melt and aerating the diluted melt to oxidize and precipitate the'dye, .or by addition of amineralacid to the melt. The sulphide present at theend of'the sulphuration is decomposed, resulting in the precipitation of some free sulphur along with the dye.

The invention accordingly comprises the several steps andthe relation of oneor more of such steps with respect to each of the others, and the product possessing the features, properties, and the relation of .constituents, which are exemplifled in the following detailed disclosure, and the scope of the invention will be indicated in the claims. n" f g In the practiceof the present inventionuse may be made of a polysulphide notlower than the pentasulphide of an alkali-forming metal in blue on exposure to the air.

ing probable formula:

wherein Y represents hydrogen or an alkyl group, and wherein the benzene nuclei may contain substituents other than halogen to obtain new'sulphide soluble dyes. The dyes so produced are, in the dry form, dark blue powders, soluble in caustic alkali, solublein concentrated sulphuric acid with a blue solution, anddiihc'ultly soluble in cold aqueous sodium sulphidesolution with an olive color which does-not change on boiling,'and from which solution unmordanted cotton is dyed in shades varying from gray to olive, which turn Further thedyes,obtaineduaccording,to the dyes which may be made in a similar manner from the above mentioned intermediate but in the preparation of which a sulphide lower than the pentasulpln'de, for example tetrasulphide, has been utilized.

Preferably, the amount of sulphur and alkali used, andthe proportion of the resulting polysulphide employed to that ofindophenol, is such that atthe end of the sulphuration there is present asulphide which corresponds approximately to the tetrasulphide. Upon decomposing this tetrasulphide; as for example, by blowi'ng "air through the solution, aidecornposition takes place,

probably according to the following equation:

resulting the precipitation"of an excessive amount of free sulphur along with the dye. In a similar manner, free sulphur is also precipitated by decomposition of, sulphides higher or lower of the sulphuration the unreacted polysulphide is presentin a form correspondingapproximately invention have a higher tinctorial value than the llO to a tetrasulphide, by dissolving or holding in solution the sulphur liberated by the decomposition of the sulphide. This may be accomplished by the addition of an alkali to the sulphuration melt at thecompletion of the sulphuration eitherbefore, after or during the decomposition of the sulphide if the method of decomposition by aeration is used. When the sulphide is decomposed by acid, it may be added after decomposition of the sulphide and is followed by aeration. By

blowing the diluted sulphuration melt with air, in the presence of an alkali (the term alkalris' meant to include alkali metal hydroxide, alkalimetal carbonate and alkali metalmonosulphida all of which have an alkaline reaction), the sul-' phur liberated according to Equation (1) reacts with the alkali and oxygen to form thiosulphate. The following three equations show the probable reaction of sulphur with caustic soda-sodium carbonate and sodium sulphide respectively.

As illustrative embodiments of a manner in which the invention may be practiced. the following examples are givenz'The parts are by weight.

Example 1 is then slowly added to the polysulphide solution at 100 to 110 0., about 15 to 20 minutes being required for the addition. The charge, which corresponds to-3.5 mols NazSs per mol of indophenol, is then heated to vigorous boiling and the boiling point adjusted to 115 C. by evaporating off water or by adding water thereto as conditions may necessitate. Agitation is carried on throughout the sulphuration. The reaction mixture is then boiled at 115 C. for about 10 to 12 hours, or until a test shows the absence of indophenol. Heating is continued for a short time after the disappearance of the indophenol to insure complete reaction.

.It will be realized that the time required for the completion of the sulphuration is dependent not only on the temperatures employed, but also upon the rate at which the reaction mass is boiled.

The temperatures preferably. utilized are those from about 105 to 120 C. and the rate of boiling is such that the time required to complete the sulphuration ranges from about 5 to 25 hours.

Isolation.The sulphuration melt thus obtained is diluted with 10,000 parts'water .and a concentratedsolution containing 267 parts caustic soda is gradually added thereto while the melt is being aerated, until the dye is substantially all precipitated, after which it is filtered, washed and dried.

The dye, when dry, is a dark blue powder soluble in concentrated sulphuric acid with a blue solution, slightly soluble in caustic alkali solution, soluble in aqueous sodium sulphide solution with an -o1ivecoloration from which solution it dyes unmordanted cotton in gray to olive shades which, upon exposure to the atmosphere, are oxidized to blue.

Example 2 Sulphumtion-A polysulphide is prepared from 386'parts fused sodium sulphide (containing 60 percent N8.2S ),.230 parts water and 4'76 parts ground sulphur. 180 parts of the indophenol described in Example 1, in the form of a paste containing 30 per cent indophenol is then added 'at. 100 to 105 C. during a period of about 15 "to 20 minutes.

The charge which corresponds to 3.5 mols NazSa per mol of indophenol, is heated to simmering temperature which is adjusted to 110 C; by evaporating water'or by adding water thereto as the conditions may necessitate. Heating at simmering temperature (i. e., just under or at the boiling point) is continued until a test shows the absence of indophenol. About 16 to 18 hours are required for the reaction to go to completion.

:IsoZation.-Thc sulphuration melt, after completion ofthe sulphuration, is diluted with 8,000 to 10,000 parts waterand the resulting solution is aerated until precipitation of the dye is completed. The mixture is then heated to to 90" C. and 255 parts soda ash is added. Aera- "tion is then continued at thistemperature until the sulphur 'is substantially dissolved, about 8 to 9 hours being required: The dye obtained is filtered and dried. Its properties correspond to thosei of thedye produced in Example 1 except that. the dyeings on cotton are a more greenish shade of blue.

' As above indicated,- the polysulphide may be preparedby dissolving free sulphur in sodium sulphide, in which case the polysulphide is formed probably according .to the following equation:

or it may be prepared by dissolving free sulphur in' caustic soda in which case the polysulphide is formed probably according to the following equation:

s.) 6NaOH+ (ax-+2) s: zNmsx -Nazswwnno wherein a: is 5 or greater. There is some indicationthat in the presence of caustic soda in excess of that required in Equation (6) to form the tetrasulphide, the tetrasulphide nevertheless will be formed at first leaving the excess of caustic unreacted on. It is also possible that in the presence, of sulphur in excess of that required in Equations (5) and (6) to form the tetrasulphide, a higher polysulphide-may not be formed, but theexcesssulphur becomes dissolved or suspended in the polysulphide formed. Therefore, the expression polysulphide,throughout the specification and claims, is used to designate the formula NazSX Without regard to whether the sulphur represented by the symbol-SK is chemically combined to form a true compound, or is partly combined, or is partlysuspended or dissolved in the alkali or polysulphide or is present in any which increase I am unable definitely to explain.

The theory I advance, butito which theory it will be understood my invention is not limited, is that the-more efiective sulphurizing agent is a solution or suspension of sulphur in sodium tetrasulphide. Therefore, in the sulphuration, I use suffic'ient sulphur together with the alkali so that at the end of the sulphuration the sulphide remaining will be present'in a iorm'corresponding approximately to the tetrasulphide. In this way it is possible to maintain at'all times in the sulphuration melt a polysulphide corresponding to or higher than the tetrasulphide.

When sodium sulphide and sulphur are used as the sulphurizing agent, the proportion of sulphurizing agent to indophenol for a fixed weight of indophenol can be calculated from Equation (5). When caustic soda and sulphur are used as the sulphurizing agenethe proportion of sulphurizing agent to indopheriol fora fixed weight of indophenol' can be calculated irom' Equation (6). It is readily apparent that iitetrasulphide ispresent at the end of the sulphuration, and if this tetrasulphidexisto,be decomposed in or duririgthe precipitation of the dye, it 'isdesirable to havepresent at theend; of the sulphuration as little polysulphide as possible in order to avoid the presence of an excessive amount of free sulphur in the dye precipitated; On the other hand, when the proportion of polysulphide to indophenol becomes too low, the sulphuration mass loses its homogeneityand' it becomes difficult to duplicate results. Between these two'lirnits lie the preferredconditionsof operation. r In order to obtain maximum yields of dye it is 1 also necessary :tofprovidesuificient available sulphur, i. e., sulphur above that needed to form nazsl, the thiosulphate sulphur not b'eing available, for the sulphuration-melt so that the reaction may go substantially to completion. It follows, thereforeythat' the lower the proportion of polysulphide to indophenol used, the higher will be the sulphur ratio-of the polysulphide neededand the higher the proportion'of polysulphide to indophenol used; the lowerwill bethe sulphur ratio of the polysulphide needed. The sulphur ratio of the polysulphide'multiplied by the ratio of the mols polysulphide to mols indophenol need not necessarily beconstant, but I prefer to have present about ,7 atomic "proportions of available sulphur per mol oi indophenol. I may use a polysulphide corresponding to a' composition higher than Nazssupto Naism or higher. The upper limit will be determined by operating considerations. a

As pointed out in Example 1 the isolation of the dye is preferably carriedout'by gradually adding the alkali, when caustic alkali 'isusedto the diluted sulphuration meltywhile it is being aerated. According to Example 2, the preferred procedure is to aerate thediluted melt to precipitate the dye, then add alkalL-when sodium carbonate is used, to the resulting mixture heated to about -90 C. and aerate further at this temperature to re-dissolve the sulphur which has been precipitated. The process for the re-solution' of the sulphur isnot limited to the temperaturespecified, although the action of alkalis, particularly of soda ash, on sulphur is'more rapid at elevated temperatures. However, the sulphur is held in solution during thesubsequent step of filtration. The quantity of alkali used for holding the sulphur in solution is such that it will react with the free sulphur which would be precipitated if no alkali, were used at this stage of the process. This quantitywill vary depending on the kind of alkali used and can be calculated from Equation (1) in conjunction with Equations (2), (3) and (4). If desired, only a partof the free sulphur need be removed.

Since certain changes in carrying out the above process, and certain modifications in the composition which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in' a limiting sense. It will. be understood that the process of removing or eliminating excess sulphur from sulphur dye melts is not limited to the treatment of the particular sulphur dyesdisclosed in the examples, nor to the treatment ofsulphurationmelts containing any particular composition of polysulphide.

In the specification and claims, the word"sulphide is used to generically include either the monosulphide or polysulphide unless otherwise stated.

I claim:

1. A process for the production of a sulphur dye soluble in aqueous sodium sulphide, which comprises heating an 'indophenol having the composition represented by the general formula wherein Y may represent hydrogen or an alkyl group, and wherein the benzene nuclei may contain substituents other thanhalogen, with sulphur and caustic soda in proportions corresponding to a polysulphide not lower than that represented by the formula Nazss, theamount of sul- 1 phur being such'that at theend of the sulphuration unreacted sodiumpolysulphide is present in a form not lower than the tetrasulphide.

3. A processfor the production of a sulphur dye soluble in aqueous sodium sulphide, which 1'.

comprises heating an indophenol having the composition represented by thegeneral formula wherein Y may represent hydrogen or an alkyl group, and wherein the benzene nuclei may contain substituents other than halogen, with a higher polysulphide of an alkali-forming metal than the tetrasulphide in such proportions that at the end of the sulphuration unreacted polysulphide is present in a form corresponding approximately to the tetrasulphide.

4. A process for theproduction-of a sulphur dye soluble in aqueous sodium sulphide, which comprises heating an indophenol having the com position represented by the general formula with sulphur and a caustic alkali in such proportions that at the end of the sulphuration unreacted alkali metal polysulphide is present in a form corresponding approximately to the tetrasulphide.

6. A process for the production of a sulphur dye soluble in aqueoussodium sulphide, which comprises heating an indophenol having the composition represented by the formula .W NE ZO with an alkali metal polysulphide not lower than the pentasulphide, the amount of sulphur being such that at the end of the sulphuration unreacted alkali metal polysulphide is present in the form of a polysulphide not lower than the tetrasulphide.

'7. A process for the production of a sulphur dye soluble in aqueous sodium sulphide, which comprises heating an indophenol having the composition represented by the formula I CH with sulphur and caustic soda in such proportions that the reaction mixture will correspond to approximately 3.5 mols N azse per mol of indophenol.

8. A process for the production of a sulphur dye, which comprises heating an indophenol with a higher polysulphide of an alkali-forming metal than the tetrasulphide in such proportions that at the end or" the sulphuration unreacted sulphide is present in aform corresponding approximately to a tetrasulphide, whereby a solution containing the sulphur dye and the sulphide is produced, and decomposing the sulphide by oxidation to precipitate the dye in the presence of an alkali in an amount sufficient to hold substantially all of the liberated sulphur in solution.

9. In the production of a sulphur dye by a process which comprises heating an indophenol with a polysulphide of an alkali forming metal, to produce a solution containing the sulphur dye and a sulphide of the alkali forming metal, anddecomposing the sulphide to precipitate the dye, whereby free sulphur is liberated, the improvement which comprises oxidizing the liberated sulphur in the presence of an alkali in an amount suiiicient to dissolve substantially all of the liberated sulphur, and separating the precipitated dye from the resulting solution.

10. In the production of a sulphur dye by a process which comprises heating an indophenol having the composition represented by the general formula where Y may represent hydrogen or an alkyl group, and wherein the benzene nuclei may contain substituents other than halogen, with a polysulphide of an alkali forming metal, to produce a solution containing the sulphur dye and a sulphide of the alkali forming metal, and decomposing the sulphide to precipitate the dye, whereby free sulphur is liberated, the improvement which comprises oxidizing the liberated sulphur in the presence of an alkali in an amount sufiicient to dissolve substantially all of the liberated sulphur, and separating the precipitated dye from the resulting solution.

11. In the production of a sulphur dye by a process which comprises heating an indophenol with an alkali metal polysulphide, to produce a solution containing the sulphur dye and a sulphide of the alkali metal, and decomposing the sulphide to precipitate the dye, whereby free sulphur is liberated, the improvement which comprises oxidizing the liberated sulphur in the presence of an alkali selected from the group consisting of sodium hydroxide, sodium carbonate and sodium sulphide in an amount suficient to dissolve substantially all of the liberated sulphur, and separating the precipitated dye from the resulting solution.

12. A process for the production of a sulphur dye, which comp-rises heating an indophenol with a higher polysulphide of an alkali-forming metal than the tetra-sulphide in such proportions that at the end of the sulphuration unreacted sulphide is present in a form corresponding approximately to the tetrasulphide, whereby a solution containing the sulphur dye and the sulphide is produced, and decomposing the sulphide by oxidation to precipitate the dye in the presence of sufficient caustic soda to hold the liberated sulphur in solution.

13. A process for the production of a sulphur dye, which comprises heating an indophenol having the composition represented by the general formula wherein Y may represent hydrogen or an alkyl 1 ulphur is liberated, adding an alkali in an caustic soda to holdetheliberated sulphur, in so: lution.

14. A processfor the production of a sulphide soluble sulphur dye which comprisesheating an indophenol having *the composition represented by the formula:

tefr

with" sulphur and caustic soda in such proportions asrtojcorrespond to 3:5 mols pass permol of in dophenol, dilutingthe melt'with water ,-aerating the diluted melt to decompose the remaining polysulphide and precipitate the dye, and adding sufficient caustic soda to the diluted melt during aeration to maintain the liberated sulphur in solution.'*

15, In the production of a sulphur dy'e'by a process which comprises heating an indophenol with a polysulphide, whereby a solution containing the sulphur dye and a sulphide is produced, the improvement which comprises decomposing the remaining sulphide by oxidation to precipitate the dye in the presence of sufficient caustic soda to hold substantially all of the liberated sulphur in solution.

16. As a new composition of matter the sulphur dye which is obtainable by heating an indophenol having the composition represented by ly soluble in cold aqueous sodium sulphide solucipitated,

J is,

the general formula wherein Y may represent hydrogen or an alkyl group, and wherein the benzene nuclei may contain substituents other than halogen, with a polysulphide of an alkali forming metal not lower than the pentasulphide, and which, in the dry state, is a dark blue powder, soluble in concentrated sulphuric acid with a blue solution, slightly soluble in caustic alkali solution, difiiculttion with an olive color which remains unchanged on boiling, and which dyes unmordanted cotton, from a sodium sulphide solution, shades varying from gray to olive, which turn blue on exposure to the air.

1'7. In the production of a sulphur dye by a process which comprises heating an indophenol with a polysulphide of an alkali-forming metal, whereby a solution containing the sulphur dye and a sulphide of an alkali-forming metal is produced, the improvement which comprises aerating the solution in the presence of sufiicient alkali to retain substantially all of the liberated sulphur in solution while the sulphur dye is pre- 18. A process for the production of a sulphur ,dye, which comprises heating an indophenol with a higher polysulphide of an alkali metal than the tetrasulphide in such proportions that at the end of the sulphuration unreacted sulphide is present in a form corresponding approximately to the tetrasulphide, whereby a solution containing the sulphur dye and the sulphide is produced, oxidiz- Y ing the sulphide to precipitate the dye, whereby amountsufficient to convert substantially all of the liberated sulphur to a thiosulphate upon oxiseparating the precipitated dye from theresultin 'so uuonk [j .19. A process for the production of a sulphur dye, which comprises heating an indophenolhaving the composition represented by 'the"general formula v where Y may represent hydrogen; or art. a'lk'y'l grounand wherein ,the benzene nuclei, may con; tain" substituents other than, halogen, with a higher 'polys'ulphide of an alkali metallthan'the tetrasulph'ide' in such proportions, that'at the end eithe sulphuration unrea'ctedlsulphide is present in, a form"corr,espondirig approximately to a tetrajsulpliide, .whereby' a solution, containing'the s'ulphurdye and the sulphide is produced, aerating the solution to precipitate the dye and decompose the sulphide, whereby free sulphur is liberated, adding an alkali selected from the group consisting of sodium hydroxide, sodium carbonate and sodium sulphide in an amount suflicient to convert substantially all of the liberated sulphur to sodium thiosulphate, aerating the resulting mixture to oxidize the liberated sulphur to sodium thiosulphate, and then separating the precipitated dye from the resulting solution.

20. In the production of a sulphur dye by a process which comprises heating an indophenol with an alkali metal polysulphide to produce a solution containing the sulphur dye and a sulphide of the alkali metal, the improvement which comprises oxidizing the sulphide to precipitate the dye in the presence of an alkali in an amount sufiicient to hold in solution substantially all of the sulphur thereby liberated.

21. A process for the production of a sulphur dye soluble in aqueous sodium sulphide, which comprises heating at a temperature of about 105 to about C. an indophenol having the composition represented by the formula comprises simmering at a temperature of about 110 C; a reaction mixture containing an indophenol having the composition represented by the formula per mol of indophenol, continuing the simmering until a test shows absence of the indophenol, and then recovering the resulting dyestuff.

dye soluble in aqueous sodium sulphide, which r 14 and an aqueous solution of about 3.5 mols NazSs 23. A process for the production of a sulphur 15a dye soluble in aqueous sodium sulphide, which comprises heating an aqueous mixture of an indophenol having the composition represented by the formula and about 3.5 mols' NazSe per mol of indophenol to a temperature of about 110 to about 115 C., adjusting the quantity of water in the reaction mixture to correspond with a boiling point of about 110 to about 115 C., boiling the resulting reaction mixture at said temperature until a test shows absence of the indophenol, and then recovering the resulting dyestuff.

24. A process for the production of a sulphur dye soluble "in aqueous sodium sulphide, which comprises boiling at a temperature of about 110 to about 115 C. an ind'ophenol having the cornposition represented by the formula 

